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61.
张利 Li-Gong Mi Long Xu Ming Zhang Dan-Yang Li Xiang Liu Feng Wang Yi-Fan Xiao Zhong-Zu Wu 《天文和天体物理学研究(英文版)》2021,(3):117-127
A sky model from CLEAN deconvolution is a particularly effective high dynamic range reconstruction in radio astronomy,which can effectively model the sky and remove the sidelobes of the point spread function(PSF)caused by incomplete sampling in the spatial frequency domain.Compared to scale-free and multi-scale sky models,adaptive-scale sky modeling,which can model both compact and diffuse features,has been proven to have better sky modeling capabilities in narrowband simulated data,especially for large-scale features in high-sensitivity observations which are exactly one of the challenges of data processing for the Square Kilometre Array(SKA).However,adaptive scale CLEAN algorithms have not been verified by real observation data and allow negative components in the model.In this paper,we propose an adaptive scale model algorithm with non-negative constraint and wideband imaging capacities,and it is applied to simulated SKA data and real observation data from the Karl G.Jansky Very Large Array(JVLA),an SKA precursor.Experiments show that the new algorithm can reconstruct more physical models with rich details.This work is a step forward for future SKA image reconstruction and developing SKA imaging pipelines. 相似文献
62.
<正>A period of extreme rainfall occurred from 17 to 22 July 2021 in Henan Province of China where the accumulated precipitation in the 6-day period exceeded 1000 mm, which is more than the mean annual precipitation in the region. The rainfall was particularly intense on 20 July 2021, especially over Zhengzhou City, the capital of Henan Province and home to more than 10 million people. Hourly rainfall of 201.9 mm was measured at a station in Zhengzhou, breaking the station hourly rainfall r... 相似文献
63.
SU Feng ~ ZHANG Shicui ~ * YANG Ming ~ LI Hongyan~ . Department of Bioengineering & Pharmaceutics Qingdao University of Science & Technology Qingdao China . Department of Marine Biology Ocean University of China Qingdao China 《海洋学报(英文版)》2006,25(5)
1 IntroductionAcetamiprid (( E)-N1-[( 6-chlor-3-pyridyl )methyl]-N2-cyano-N1-methylacetamidine), a cyano-substituted neonicotinoid compound ( Kagabu,1999), is a relatively newclass of insectide, exhibi-ting a broad insecticidal spectrum ( Matsunaka,2000; … 相似文献
64.
INTRODUCTIONThe coast zone is the area where most human activities take place and where the highest economic benefit is produced. The knowledge of the distribution and variation of primary production provides the bases as reference helping the marine exploitation and management. 相似文献
65.
LIU Chang MA Qing Xin CHU Bi Wu LIU Yong Chun HE Hong ZHANG Xiao Ye LI Jun Hua HAO Ji Ming 《中国科学:地球科学(英文版)》2015,(2):245-254
As an important anthropogenic volatile organic compound(VOC), m-xylene has attracted numerous attentions due to its potential in secondary organic aerosol(SOA) formation. In this study, effects of aluminium dust seeds(boehmite and alumina) on SOA yield and aerosol size in m-xylene/NOx photo-oxidation were investigated in a 2 m3 smog chamber at 30°C and 50% relative humidity. Compared to the seed-free system, the presence of aluminium seeds resulted in an increase in the SOA yield, and also enhanced the O3 concentration in the chamber. The photolysis of O3 is a major source of OH radical, which is the most important oxidant of m-xylene. The increase in O3 concentration could result in the generation of more OH radicals, and finally contribute to the SOA formation. Seed particles influence the SOA size mainly by acting as condensation nuclei. Semi-volatile organic compounds(SVOCs) were condensed onto these nuclei, resulting in the increase in SOA size. However, when aluminium seeds with high concentrations were introduced into the system, SVOCs that had been condensed onto each particle were dispersed by these seeds, leading to the reduction in aerosol size. 相似文献
66.
1 INTRODUCTION The distance to the Galactic center R0 is a fundamental constant for astronomy and astrophysics. Most determinations of astronomical quantities are directly connected with the Galactic distance scale, e.g., the rotational speed of our Galax… 相似文献
67.
The South Coast Plain of Laizhou Bay adjoins southward the mountains and hills of the Central Shandong Province, extends eastward to the Jiaolai Plain, reaches northward to Laizhou Bay of the Bohai Sea and westward to the Yellow River Delta. All the lower reaches of the Mihe River, the Weihe River and the White wave River are so apt to deposit, burst and move that widespread palaeochannels have taken form,which have rarely been studied(JIA,1985). It is the purpose of this paper to … 相似文献
68.
Tungsten(or wolfram,W),one of the crucial metal sources,is widely used in electronics,oil,chemical and military industries.China owns abundant tungsten resources(~60%of the world reserves and~80%of the world’s production),of which the area from Southern Jiangxi-Northern GuangdongSouthern Hunan is the most significant ore belt in south China.Understanding ore genesis and distribution as well as the process of fine mineralization will further benefit the prospecting and exploration of tungsten deposits.The accurate determination of the age of mineralization is at the front line in the study of ore deposit and the premise for solving and understanding the above problems. 相似文献
69.
We studied pot cultivated Haloxylon ammodendron’s growth, physiological changes and drought resistance under NaCl, H2SiO3,
and NaCl+H2SiO3 treatments. Results show that 0.3 g/kg NaCl, 0.2 g/kg H2SiO3 or 0.3 g/kg NaCl+0.1 g/kg H2SiO3 treatments can
effectively promote growth and improve the drought resistance of H. ammodendron. Compared with that without NaCl treatment,
H. ammodendron’s height, crown diameter and fresh weight increased by 42%, 91% and 62% respectively under 0.3 g/kg NaCl
treatment, and its main stem diameter, main root diameter and main root length increased by 40%, 39% and 23%, respectively.
Compared with that without H2SiO3 treatments, H. ammodendron’s height, crown diameter and fresh weight increased by 36%,
45% and 27% respectively under 0.2 g/kg H2SiO3 treatment, and its main stem diameter, main root diameter and main root length
increased by 23%, 23% and 20%, respectively. Compared with that under 0.3 g/kg NaCl treatment, H. ammodendron’s height,
crown diameter and fresh weight and main root length increased by 9%, 10%, 17% and 12% respectively under 0.3 g/kg
NaCl+0.1 g/kg H2SiO3 treatment. Compared with that under 0.1 g/kg H2SiO3 treatment, H. ammodendron’s height, crown diameter
and fresh weight increased by 28%, 76% and 68% respectively under 0.3 g/kg NaCl+0.1 g/kg H2SiO3 treatment, and its main
stem diameter, main root diameter and main root length increased by 30%, 32% and 27%, respectively. This suggests that moderate
levels of NaCl+H2SiO3 interaction can effectively promote growth and improve drought resistance of H. ammodendron than
separate applications of NaCl or H2SiO3. 相似文献
70.
Study on the Dynamic Process of the Onset of South China Sea Summer Monsoon 总被引:1,自引:0,他引:1 下载免费PDF全文
By using the NCEP/NCAR reanalysis data from 1958 to 1997, we first looked into the atmospheric flow conditions in the one month immediately prior to the onset of the South China Sea summer monsoon (SCSSM) each year. A monthly-averaged zonal basic flow of 40-yr composite was then calculated. The stability of Rossby wave in the basic flow was studied based on the spherical barotropic vorticity equation. Furthermore, the spectral function expansion method was adopted to define and compute the evolvement of a developing wave packet. The results indicate that there exists barotropic instability of spherical Rossby wave in the climatically-averaged flow field before the SCSSM onset. The instability is triggered by the westerly jet stream in the Southern Hemisphere, and the strongest instable perturbation lies to the south of the westerly jet stream. The peak of the developing spherical Rossby wave packet propagates from mid and high latitudes to low latitudes, though not crossing the equator, spurring the cumulus convection in the tropical zones. The eruption of the cumulus convection and its spread to monsoon regions help to speed up the adjustment of the general circulation and the SCSSM onset. It is concluded that elements that contribute to the SCSSM onset are on global scale, albeit the onset itself looks like a local phenomenon. 相似文献